記述言語：英語   出版者・発行元：Journal of Neuroscience  

Multifaceted microglial functions in the developing brain, such as promoting the differentiation of neural progenitors and contributing to the positioning and survival of neurons, have been progressively revealed. Although previous studies have noted the relationship between vascular endothelial cells and microglia in the developing brain, little attention has been given to the importance of pericytes, the mural cells surrounding endothelial cells. In this study, we attempted to dissect the role of pericytes in microglial distribution and function in developing mouse brains. Our immunohistochemical analysis showed that approximately half of the microglia attached to capillaries in the cerebral walls. Notably, a magnified observation of the position of microglia, vascular endothelial cells and pericytes demonstrated that microglia were preferentially associated with pericytes that covered 79.8% of the total capillary surface area. Through in vivo pericyte depletion induced by the intraventricular administration of a neutralizing antibody against platelet-derived growth factor receptor (PDGFR)b (clone APB5), we found that microglial density was markedly decreased compared with that in control antibody-treated brains because of their low proliferative capacity. Moreover, in vitro coculture of isolated CD11b1 microglia and NG21PDGFRa– cells, which are mostly composed of pericytes, from parenchymal cells indicated that pericytes promote microglial proliferation via the production of soluble factors. Furthermore, pericyte depletion by APB5 treatment resulted in a failure of microglia to promote the differentiation of neural stem cells into intermediate progenitors. Taken together, our findings suggest that pericytes facilitate microglial homeostasis in the developing brains, thereby indirectly supporting microglial effects on neural progenitors.

DOI： 10.1523/JNEUROSCI.1201-21.2021

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記述言語：英語   出版者・発行元：Anatomical Science International  

Microglia are the resident immune cells of the central nervous system. Microglial progenitors are generated in the yolk sac during the early embryonic stage. Once microglia enter the brain primordium, these cells colonize the structure through migration and proliferation during brain development. Microglia account for a minor population among the total cells that constitute the developing cortex, but they can associate with many surrounding neural lineage cells by extending their filopodia and through their broad migration capacity. Of note, microglia change their distribution in a stage-dependent manner in the developing brain: microglia are homogenously distributed in the pallium in the early and late embryonic stages, whereas these cells are transiently absent from the cortical plate (CP) from embryonic day (E) 15 to E16 and colonize the ventricular zone (VZ), subventricular zone (SVZ), and intermediate zone (IZ). Previous studies have reported that microglia positioned in the VZ/SVZ/IZ play multiple roles in neural lineage cells, such as regulating neurogenesis, cell survival and neuronal circuit formation. In addition to microglial functions in the zones in which microglia are replenished, these cells indirectly contribute to the proper maturation of post-migratory neurons by exiting the CP during the mid-embryonic stage. Overall, microglial time-dependent distributional changes are necessary to provide particular functions that are required in specific regions. This review summarizes recent advances in the understanding of microglial colonization and multifaceted functions in the developing brain, especially focusing on the embryonic stage, and discuss the molecular mechanisms underlying microglial behaviors.

DOI： 10.1007/s12565-021-00631-w

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記述言語：日本語   出版者・発行元：公益社団法人 日本薬学会  

脳には、神経系の細胞の他にも免疫細胞であるミクログリアが存在し、脳の機能を支えている。ミクログリアは胎生期から神経系細胞の分化や配置を制御し、脳発達に貢献していることが明らかにされつつある。胎生期の大脳実質において、ミクログリアは胎齢の進行に伴い分布を変化させる。本稿では、最近筆者らが報告したマウス胎生期の大脳実質内におけるミクログリアの移動メカニズムと、その生理学的意義についての研究内容を中心に紹介する。

DOI： 10.14894/faruawpsj.58.9_868

CiNii Research

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Nature Communications  

In the developing cortex, postmigratory neurons accumulate in the cortical plate (CP) to properly differentiate consolidating subtype identities. Microglia, despite their extensive surveying activity, temporarily disappear from the midembryonic CP. However, the mechanism and significance of this absence are unknown. Here, we show that microglia bidirectionally migrate via attraction by CXCL12 released from the meninges and subventricular zone and thereby exit the midembryonic CP. Upon nonphysiological excessive exposure to microglia in vivo or in vitro, young postmigratory and in vitro-grown CP neurons showed abnormal differentiation with disturbed expression of the subtype-associated transcription factors and genes implicated in functional neuronal maturation. Notably, this effect is primarily attributed to interleukin 6 and type I interferon secreted by microglia. These results suggest that “sanctuarization” from microglia in the midembryonic CP is required for neurons to appropriately fine-tune the expression of molecules needed for proper differentiation, thus securing the establishment of functional cortical circuit.

DOI： 10.1038/s41467-020-15409-3

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Development Growth and Differentiation  

Morphogenesis and organ development should be understood based on a thorough description of cellular dynamics. Recent studies have explored the dynamic behaviors of mammalian neural progenitor cells (NPCs) using slice cultures in which three-dimensional systems conserve in vivo-like environments to a considerable degree. However, live observation of NPCs existing truly in vivo, as has long been performed for zebrafish NPCs, has yet to be established in mammals. Here, we performed intravital two-photon microscopic observation of NPCs in the developing cerebral cortex of H2B-EGFP or Fucci transgenic mice in utero. Fetuses in the uterine sac were immobilized using several devices and were observed through a window made in the uterine wall and the amniotic membrane while monitoring blood circulation. Clear visibility was obtained to the level of 300 μm from the scalp surface of the fetus, which enabled us to quantitatively assess NPC behaviors, such as division and interkinetic nuclear migration, within a neuroepithelial structure called the ventricular zone at embryonic day (E) 13 and E14. In fetuses undergoing healthy monitoring in utero for 60 min, the frequency of mitoses observed at the apical surface was similar to those observed in slice cultures and in freshly fixed in vivo specimens. Although the rate and duration of successful in utero observations are still limited (33% for ≥10 min and 14% for 60 min), further improvements based on this study will facilitate future understanding of how organogenetic cellular behaviors occur or are pathologically influenced by the systemic maternal condition and/or maternal-fetal relationships.

DOI： 10.1111/dgd.12648

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掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：eNeuro  

Microglia, the resident immune cells in the CNS, play multiple roles during development. In the embryonic cerebral wall, microglia modulate the functions of neural stem/progenitor cells through their distribution in regions undergoing cell proliferation and/or differentiation. Previous studies using CX3CR1-GFP transgenic mice demonstrated that microglia extensively survey these regions. To simultaneously visualize microglia and neural-lineage cells that interact with each other, we applied the in utero electroporation (IUE) technique, which has been widely used for gene-transfer in neurodevelopmental studies, to CX3CR1-GFP mice (males and females). However, we unexpectedly faced a technical problem: although microglia are normally distributed homogeneously throughout the mid-embryonic cortical wall with only limited luminal entry, the intraventricular presence of exogenously derived plasmid DNAs induced microglia to accumulate along the apical surface of the cortex and aggregate in the choroid plexus. This effect was independent of capillary needle puncture of the brain wall or application of electrical pulses. The microglial response occurred at plasmid DNA concentrations lower than those routinely used for IUE, and was mediated by activation of Toll-like receptor 9 (TLR9), an innate immune sensor that recognizes unmethylated cytosine-phosphate guanosine motifs abundant in microbial DNA. Administration of plasmid DNA together with oligonucleotide 2088, the antagonist of TLR9, partially restored the dispersed intramural localization of microglia and significantly decreased luminal accumulation of these cells. Thus, via TLR9, intraventricular plasmid DNA administration causes aberrant distribution of embryonic microglia, suggesting that the behavior of microglia in brain primordia subjected to IUE should be carefully interpreted.

DOI： 10.1523/ENEURO.0312-18.2018

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Genes to Cells  

Neocortical development proceeds through the formation of new zones in which neural-lineage cells are organized based on their differentiation status. Although microglia initially distribute homogeneously throughout the growing cerebral wall, they accumulate in the inner cytogenic zone, the ventricular zone (VZ) and the subventricular zone (SVZ) in the mid-embryonic stage. However, the roles of these cells remain to be elucidated. In this study, we found that microglia, despite being only a minor population of the cells that constitute the cerebral wall, promote the differentiation of neural progenitor cells by frequently moving throughout the cortex; their migration is mediated by the CXCL12/CXCR4 system. Pulse-chase experiments confirmed that microglia help Pax6+ stem-like cells to differentiate into Tbr2+ intermediate progenitors. Further, monitoring of microglia by live imaging showed that administration of AMD3100, an antagonist of CXCR4, dampened microglial movement and decreased microglial surveillance throughout the cortex. In particular, arrest of microglial motion led to a prominent decrease in the abundance of Tbr2+ cells in the SVZ. Based on our findings, we propose that extensive surveillance by microglia contributes to the efficient functioning of these cells, thereby regulating the differentiation of neural stem-like cells.

DOI： 10.1111/gtc.12632

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：JCI Insight  

In the central nervous system, endothelial cells (ECs) and pericytes (PCs) of blood vessel walls cooperatively form a physical and chemical barrier to maintain neural homeostasis. However, in diabetic retinopathy (DR), the loss of PCs from vessel walls is assumed to cause breakdown of the blood-retina barrier (BRB) and subsequent vision-threatening vascular dysfunctions. Nonetheless, the lack of adequate DR animal models has precluded disease understanding and drug discovery. Here, by using an anti-PDGFRβ antibody, we show that transient inhibition of the PC recruitment to developing retinal vessels sustained EC-PC dissociations and BRB breakdown in adult mouse retinas, reproducing characteristic features of DR such as hyperpermeability, hypoperfusion, and neoangiogenesis. Notably, PC depletion directly induced inflammatory responses in ECs and perivascular infiltration of macrophages, whereby macrophage-derived VEGF and placental growth factor (PlGF) activated VEGFR1 in macrophages and VEGFR2 in ECs. Moreover, angiopoietin-2 (Angpt2) upregulation and Tie1 downregulation activated FOXO1 in PC-free ECs locally at the leaky aneurysms. This cycle of vessel damage was shut down by simultaneously blocking VEGF, PlGF, and Angpt2, thus restoring the BRB integrity. Together, our model provides new opportunities for identifying the sequential events triggered by PC deficiency, not only in DR, but also in various neurological disorders.

DOI： 10.1172/jci.insight.90905

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（大学，研究機関等紀要）  

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）  

開催年月日： 2021年2月

記述言語：英語  

開催年月日： 2020年9月

記述言語：日本語   会議種別：口頭発表（一般）  

開催年月日： 2020年9月

記述言語：日本語   会議種別：シンポジウム・ワークショップ パネル（指名）  

開催年月日： 2020年1月

記述言語：英語   会議種別：口頭発表（一般）  

開催年月日： 2019年7月

記述言語：英語   会議種別：ポスター発表  

開催年月日： 2018年2月

記述言語：英語   会議種別：ポスター発表  

開催年月日： 2017年3月

記述言語：日本語   会議種別：口頭発表（一般）  

記述言語：英語   会議種別：ポスター発表  

記述言語：日本語   会議種別：ポスター発表  

記述言語：日本語   会議種別：口頭発表（一般）  

記述言語：日本語   会議種別：口頭発表（一般）  

記述言語：英語   会議種別：口頭発表（一般）  

記述言語：英語   会議種別：ポスター発表